The same polls showed Harris leading Trump in a head-to-head matchup by 55 to 42 per cent among voters aged 65 and older in those states.
After Biden, 81, stepped aside over concerns about his age, the Harris campaign suggested Trump's age could be an issue, too.
"Trump is now the old guy in the race, 78 years old, and he's got a few cognitive problems himself, so the shoe is completely flipped upside down here," former Democratic National Committee Chair Howard Dean said in a quote distributed by the campaign last month. Harris is 59.
Trump last week called for scrapping taxes on Social Security benefits for seniors, a position that could boost his support among that demographic, but experts say doing so could hasten the risk of insolvency for the old-age benefit plan.
The Trump campaign had no immediate response to Dean's comment or concerns raised about the impact of Trump's tax proposal on Social Security.
About 40 per cent of Americans who receive Social Security benefits pay federal income tax, according to the Social Security Administration.
Repealing the tax could increase the budget deficit by $1.6 trillion to $1.8 trillion through 2035, according to the Committee for a Responsible Federal Budget.
The Harris campaign had no immediate comment on Trump’s call to stop taxing Social Security for seniors. It noted that Trump had in the past called for cutting Social Security and Medicare. Margaret Washa, 76, a retired physical therapist from Middleton, Wisconsin, who donates regularly to Democratic candidates, said she felt momentum building for Democrats after Biden stepped aside.
"I would happily donate to a PAC called 'Boomers for Kamala & Walz'," she said.